Conventionally, a system for discriminating the expression and sequence of genes by using a DNA microarray has been proposed as disclosed in Japanese Patent Laid-Open No. 10-272000 or 11-187900. In this system, a base sequence fragment (probe) to be hybridized with a sample must be designed beforehand. The characteristic feature of the system is that if a good probe set is designed, a large amount of information can be obtained with respect to a base sequence fragment existing in a sample at a very high probability.
Unfortunately, a wide variety of base sequence fragments can exist in a sample (target) to be analyzed, and they entirely change from one experimental system to another. When that happens, an entirely different probe must be designed. Conventionally, this probe designing is performed by human efforts on the basis of experiments. However, large amounts of base sequences are now beginning to be determined, so it is becoming practically impossible to design probes by human efforts.